Adaptive optics (AO) is a technology for reducing the effect of wave-front distortions for improving the performance of optical systems. AO systems may be used to remove the effects of atmospheric distortion or optical aberrations in laser communication systems, astronomical telescopes, and retinal imaging systems. AO systems operate by measuring and compensating for distortions in a wave-front using a spatial phase modulator, such as a deformable mirror or a liquid crystal array.
Propagation of laser energy and sensor imagery is degraded by the optical effects of atmospheric path turbulence arising from both a near-field aerodynamic flow-field and free-stream atmospheric turbulence beyond the aerodynamic flow regime. AO systems in use since the 1970's attempt to reduce the effects of these two turbulence regimes on propagating optical signals; however, limitations of AO system closed-loop bandwidth and spatial resolution hamper the ability of AO systems to fully correct for path turbulence. Hence, optimization and refinement of AO systems is actively ongoing.
New developments in ultra-high speed laser communication have pushed data rates to 100 giga-bits per second (Gb/sec) or higher, yet these laser communication systems are not immune to aerodynamic and free-stream turbulence, and are subject to frequent and rapid data fades and dropouts in strong scintillation (variation in amplitude at the laser-communication optical entrance pupil). For example, laser radar (LADAR) systems rely on strong target backscatter signals for accurate range and Doppler information, and these backscatter signals are again modulated in intensity by time-varying scintillation, thereby decreasing system performance.